Pendulum CNT-90 - Page 178

Specifications
Timebase
Specifications
CNT-91R/71B
Timebase Type
Rubidium
Uncertainty due to:
-Calibration adjustment tolerance
@ +23 °C ± 3°C
<6x10
-12
-Aging:
per 24 h
per month
per year
1)
<3x10
-10
2)
<5x10
-11
3)
<3x10
-10
-Temperature variation:
0 °C - 50°C
20 °C - 26 °C (typ. values)
<1x10
-10
<2x10
-11
-Power voltage variation: ±10%
<1x10
-11
Frequency retrace
after 24h OFF time
- after 1 h ON time
- after 24h ON time
<1x10
-10
<5x10
-11
Phase noise stability:
at 1kHz offset from carrier
<-140 dBc
Short term stability:
(Root Allan Variance)

= 1 s
Typical values

= 1 0 s
<1x10
-11
<1x10
-11
Power-on stability:
-Deviation versus final value after
24 h on time, after a warm-up time
of 12 min:
<5x10
-11
Time to lock @25 °C
appr. 5 min
Total uncertainty, for operating
temperature 0°C to 45 °C,
@2 (95 %) confidence interval:
-1 year after calibration
-2 years after calibration
<3x10
-10
4)
<5x10
-10
Typical total uncertainty, for
operating temperature 20°C to 26 °C,
@2 (95 %) confidence interval:
-1 year after calibration
-2 years after calibration
<2.5x10
-10
4)
<5x10
-10
Explanations
1) After 24 hours of continuous operation, and
at a quasi-constant temperature of ± 5°C within
the operating range
2) After 3 months of continuous operation.
3) After 1
st
year, aging during 1
st
year:
<5x10
-10
; long-term < 2 x 10
-9
/ 10 years.
4) After 1 year of operation. Uncertainty
<6x10
-10
the first year of operation.
Calibration Adjustment Tolerance is the
maximum tolerated deviation from the true 10
MHz frequency after a calibration. When the
reference frequency does not exceed the
tolerance limits at the moment of calibration,
an adjustment is not needed.
NOTE: Electrical adjustment by means of
tuning voltage from DAC; no potentiometer
trimming.
Serial interface for closed-case calibration
and status reporting.
8-59
USER MANUAL ● CNT 9x Series ● Rev.22 February 2020